(CNN) -- The search continued Thursday for survivors of a boat authorities suspect was used for human smuggling that tipped over off the east coast of Florida, the U.S. Coast Guard said.
Nine people died, and 16 are in custody -- 11 aboard the Coast Guard Cutter Drummond and five on land, said Capt. Jim Fitton, the Coast Guard's sector commander in Miami, Florida.
"We still don't know how many people were out there," Fitton said at a news conference Thursday morning.
Authorities are searching a 2,700-square-mile area and have flown 11 aircraft sorties, Fitton said.
"We're going to continue searching," he said. "We're putting more and more efforts out there. As long as there's a possibility, we'll be out there."
Almost all the victims are believed to be from Haiti and the Bahamas, according to the Coast Guard, which said a dangerous number of people were packed onto a small pleasure cruiser.
Officials have not found the boat, described only as white, with a center console and two engines.
The boat flipped about 15 miles east of Boynton Beach, Florida, about 2 a.m. ET Wednesday, the Coast Guard said. Someone who saw the boat notified the agency more than nine hours later.
Women and children were on the boat, Fitton said, and a pregnant woman has been taken to a hospital.
The Rev. Luke Harrigan, a Fort Lauderdale, Florida, pastor who serves the Haitian community, is working with the Coast Guard.
Harrigan said it is not uncommon for smugglers to charge people from the impoverished nation as much as $4,000 for passage to the United States.